1. Field of the Invention
The present invention relates to an image processing apparatus for reading an image of, for example, a document by a scanner so as to process data on the read image, an image forming apparatus provided with the image processing apparatus, for forming an image, and an image forming method.
2. Description of the Related Art
In a copying machine, a printing rate is one of factors of determining toner consumption per sheet of transfer paper. The printing rate is a value determined by a printing area of a copying image in a specific evaluation chart, and it is greatly relevant to the number of dots of an image to be formed in an image forming unit. Therefore, it is possible to reduce the number of dots of the image by narrowing the width of a line of a character or the like by image processing. Consequently, the reduction of the printing rate by narrowing the width of the line by the image processing is effective in saving the toner consumption.
A line has been conventionally thinned (in other words, the width of a line has been conventionally controlled) (with respect to binary image data) after pseudo gradation processing such as error diffusion. A method for identifying an edge and a non-edge in image data has been performed by matching with a template pattern prepared in advance.
However, there has been a limit to identifying accuracy as long as the binary image data after the gradation processing has been processed, and therefore, there may be some identifying errors here and there, thereby degrading a quality of an image. Furthermore, there has arisen a problem in reducing or enlarging the image data. In the case of the reduction, the size of an output image such as a character or a thin line has become small, thereby causing a trouble such as faint printing. In contrast, in the case of the enlargement, the size of an output image such as a character or a thin line has become large, thereby causing a trouble of deterioration of a line thinning effect.